Apparatus for separating airborne asbestos material



June 1, 1954 N. J. LOCKHART APPARATUS FOR SEPARATING AIRBORNE ASBESTOS MATERIAL 2 Sheets-Sheet 1 Filed April 24, 1950 /fl J Z OC/f/ffi/P7 INVENTOR.

BY 7 M WOW;

WTTO/PNEYJ June 1, 1954 J. LOCKHART 2,679,933

APPARATUS FOR SEPARATING AIRBORNE ASBESTOS MATERIAL Filed April 24, 1950 2 Sheets-Sheet 2 New/4w ocef/mpr' Z 7 INVENTOR.

2 Zea/em xvi da Patented June 1, 1954 APPARATUS FOR SEPARATING AIRBORNE ASBESTOS MATERIAL Nathan J. Lockhart, La Moine, Calif. Application April 24, 1950, Serial No. 157,718

Claims. 1

My invention relates generally to an apparatus for processing fibrous material, and more particularly to an apparatus for separation of minerals such as asbestos from a parent rock.

In order to fully understand the function of the apparatus it is necessary to consider briefly the nature of asbestos as distinguished from other more common ores. Asbestos suitable for commercial use is found in the form of crystalline fibers imbedded in certain types of stratified rock. The value of the product is dependent upon the separability and length of the fibers, which are subsequently spun and manufactured into sheets of insulating material. For these reasons, con ventional grinding and crushing processes using water to promote the grinding are impractical, as they retard the separation of the fibers and destroy their length. Commercial operations have heretofore depended largely upon screen separation after an initial rough crushing. To produce a relatively pure product by such a method, it is n cessary to screen the ore many times, and the production costs are consequently high.

I have discovered that it is possible to produce a relatively pure and fibrous asbestos by air flotation of the mixture of asbestos and rock particles, and a subsequent separation of the rock from the fibrous asbestos. This may be done in a continuous operation for which purpose I have constructed an apparatus that requires a minimum number of operators and is otherwise economical.

Briefly described, the apparatus constructed according to my invention employs as shattering means a plurality of paddles adapted to rotate rapidly about a horizontal axis Within a cylindrical housing. Raw ore is fed into the housing and is shattered by the impact of the rotating paddles. The mixture of shattered rock and asbestos fibers is discharged vertically through an open ng in the cylindrical wall of the housing, being forced out by a blast of air created by the centrifugal blower action of the rotating paddles. As the material passes upwardly, it goes through an adjustable throat which controls the air blast, and accordingly the particle size in the mixture. An adjacent by-pass chute returns oversize particles to the rotor-housing where they are reshattered. The mixture at this state of the process consists of loose rock particles and loose fibers of asbestos. A series of sharply angled deflection passageways then cooperate with the air blast, to separate the relatively light fibers from the rock particles. The asbestos is carried upwardly for further processing, and the waste rock falls and is carried away by an exhaust system. As can be understood, the operation is rapid and continuous, resulting in a low production cost.

An object of my invention is to provide an apparatus which separates the shattered material according to size, returning all insufliciently shattered material for reprocessing.

It is also an object of my invention to provide air flotation passageways that may be quickly and easily adjusted to control the size of the particles of shattered material which are discharged.

Still other objects of my invention are to provide means for separating the crystalline fibers of asbestos from the rock particles, and to provide means for carrying the waste rock from the apparatus.

A still further object of my invention is to provide means for accurate control of the separating process which are easily adjustable to variations in the raw ore.

These and other objects and advantages of my invention will become apparent from the following detailed description of a preferred form thereof, and from an inspection of the accompanying drawing in which:

Fig. 1 is a rear elevation of a preferred form of my improved apparatus;

Fig. 2 is a partial cross-section taken along the line 2-2 of Fig. 3; and

Fig. 3 is a vertical section taken substantially along the lines 3-3 of Fig. 1.

Referring now to the drawings, the numeral i0 designates a lower base or housing section of generally rectangular box-like shape, having a horizontal attachment flange H welded around its upper edge. Supported on the base H? is a central housing section i2, which has an attachment flange i3 welded to its lower edge to mate with and be secured'to the flange H. The central housing 52 is generally box-shaped with open top and bottom, and has fiat vertical front and back walls, joined to side Walls that are partially cylindrical and partially vertical. Mounted on the top of the central housing section I2 is an enlarged generally rectangular upper housing l5 which overhangs the rear walls of the central section. A second pair of attachment flanges l6 and H are provided on the adjacent edges of the upper housing i5 and the central housing 12 respectively, to secure these members together. A suitable brace 18 may also extend rearwardly from the junction to the flanges l6 and il to 3 support the overhanging portion of the upper housing l5, as is seen in Fig. 3.

Mounted for rotation with the enclosure formed by the lower housing i6 and the central housin i2, is a hammer means formed as a multiple bladed rotor is. The rotor 25 has an axle 2! with three spaced circular discs 22 mounted coaxially thereon. Four radial projecting blade supports 23 are joined to the discs 22 and each has bolted thereon a blade 24 which is disposed parallel to the axle 2 i. The ends of the axle 21 are journaled in a pair or pillow block bearings 25 and 26 which are supported by a pair of outwardly projecting flanges 21 and 28 welded to the front and back walls of the lower housing section ill. The flanges 2'1 and 28 are positioned to substantially center the axle 2i within the enclosure formed by the housing sections it and 12.

The rotor '28 is adapted to rotate clockwise as viewed in Fig. 2, and the blades 24 are remov- O ably fastened on the forward side or the support 23 by means such as bolts 29 so that they may be quickly replaced. To drive the rotor it, a multiple pulley 3:": is secured to the rear end of the axle 21 as is best seen in Fig. 3. The pulley so is adapted to receive a number of V belts for power connection to a suitable driving source (not shown). The entire structure thus described is capable of considerable modification without departin from the scope of my invention.

On the front face of the central housing section is of the bearin 25 is an inclined loading chute 35 discharging into the interior of the housing. Material M in the form of raw ore is fed into the loading chute 35 and enters the rotor chamber in position to be struck by the rotating blades 24. The impact of the blades 2 3- on the material M shatters the ore and exposes the fibers of asbestos. The mixture of rock particles and asbestos is then carried around the housing and discharged upwardly to an opening top of the central housing l2. The rotating blades or paddles 2 act as a centrifugal blower and create an air blast to force the material upwardly. A vertical baiiie 35 is positioned within the central housing section i2 adjacent the rear edges of the blades 2d, and extends upwardly to define with the front wall of the housing a discharge opening through which the material passes.

Extending across the discharge opening or the section i2 is a rate consisting of a plurality of flat bars 3'? welded, edge up, between a pair of plate-like supports 38 and 35 and defining passageway therebetween. To further promote the shattering and reduction of the material carried around the interior of the rotor housing, a series of striker bars 49 may be welded along the interior or" the cylindrical portion of the central housing section l2, as seen in Fig. 2.

In the upper housing section i 9. fiat baffle 35 slants downwardly from the forward wall to terminate near the upper edge of the vertical bafile 36. The opening between these baliles defines a throat 46 through which the material carried upwardly by the air blast passes. On the rear face of the bafiie 35 is a sliding door or gate 51 to adjust the size of the throat as. Vertical tracks 48 guide the outer edges of the gate G7, and a bracket it extends rearwardly from the latter for a connection to an adjusting means. The bracket 39 is pivotally connected to a cranklinkage 58 mounted on a horizontal shaft 5!. The outer end of the shaft 5i carries a manual adjusting handle 52 disposed outside of the central housing section i2, as is shown in Fig. 3. The crank-linkage 5i slidably moves the gate ll against the baiile 36 while the handle 52 is adjusted to the desired angular position.

The sharp change of direction made by the upwardly moving material in passing through the throat it causes many of the heavier rock particles to be centrifugaily displaced from the air blast and fall back through the grating bars 3? to be reprocessed. As can be understood, the loose fibers of asbestos are better supported by the air blast, and these together with the smaller rock particles continue upwardly within the upper housing section is. By adjustment of the gate 3'1, the constriction of the throat it may be varied to change the velocity of the air blast in the area. This change in air velocity determines the relalve fineness of the particles which will be supported by the air blast, and may be easily varied for different types of raw ores.

The housing section it extends upwardly and rearwardly a substantial distance and has a partial vertical dividing wall or bafiie 55 spaced rearwardly from the throat '46. An additional overhanging portion extends rearwardly beyond the wall 55 to form a second enclosure or separation chamber 72, as will later be described. A horizontal bailie or wall 56 extends from the front wall of the section iii to terminate near the upper edge of the wall 553 and form a discharge throat 5?. A second gate 58 similar to the ate 4? is movable vertically to adjust the constriction of the throat 5'? being guided by vertical tracks 55 mounted on the forward face of the vertical wall 55. To adjust the gate 58, I provide an operating handle 65 on the outside of the housing i5, as is shown in the phantom outline of Fig. 3. The handle (ii) is mounted on a horizontal shaft 6! connected by a crank-linkage 62 to a projecting bracket 63 on the forward side of the gate 58. The angular position of the handle 65! thus determines the vertical position of the gate 58. As the air blast carrying the material upwardly makes a second sharp change of direction to pass through the throat 5?, still more of the rock particles are deflected and fail, while the lighter asbestos fibers and the smaller rock particles continue.

In order to return such particles as are too large to be carried through the throat 57, an opening is formed in the back of the wall of the central housing section 52 in a similar and opposite position to the feed chute 35. A slanted wall 56 extends upwardly from beneath the opening 55 to join the vertical wall 55, and form a funnel-like chute which directs the material downwardly into the opening. The particles material returning through the opening 85 will be re-impacted by the blades 2 1 until they are small enough to be supported by the air blast. By adjustment of the gate 57, the velocity of the air blast in the area may be changed so as to support larger or smaller particles of material, and hence determine the size of particles which will be returned for reprocessing. It is preferable to have sight ports 58 and 69 mounted near the discharge side of the throats 56 and il respectively, so that the operator can visually control the size of the particles which are discharged.

After leaving the throat 51' the material enters into the separation chamber 12 which is iormed as an extension on the housing iii. The chamber is is defined generally by an upper horizontal wall 13, side wall I4, and a vertical rear wall 15 spaced behind the vertical bafile 55. Below the throat the walls of the chamber 12 extend downwardly to join a hopper-like bottom having converging front and rear walls 16 and 11 joined together by a short bottom wall 18. An opening 79 is formed in the bottom wall 18 to communicats with the interior of a large discharge pipe 89 which runs horizontally outwardly as may best be seen in Fig. 1. The pipe 99 is joined to the trough bottom 18 by a short channel section 8! and may also be supported from the bracket !8. At the outer end of the pipe 89 is a blower means (not shown) which serves to exhaust the waste rock which falls during the separation process. Intake pipe means in the form of a blower pipe 82 is spaced above the discharge pipe 89 for aiding in the separation process as will later be described.

The air blast carrying the rock particles and asbestos through the throat 5'! does not enter freely into the chamber '12, but is inclined downwardly by spaced upper and lower baffles 819 and 8'! respectively. The lower bailie 8'! is fixed and extends from the lower edge of the throat 5'! to approximately the center of the chamber '32. On the outer end of the baffle 8'! is a horizontal section 99 terminated by a small upturned flange S9. As is indicated by the flow arrows of Fig. 3, the air blast is thus deflected upwardly as it leaves the bafile 87.

The upper baiiie 86 is mounted for a limited pivotal movement about a horizontal hinge means as fastened near the upper edge of the throat 5?. A crank-linkage 9| is fastened on the outer edge of the bafiie 89 for moving the latter about the hinge 99. The crank-linkage 9! is supported on a horizontal shaft 92 which extends outwardly to one side of the housing 15 and em gages a manual control handle 93. Angular movement of the handle 93 determines the spacing between the outer end of the upper baffle 86 and the lower bafiie 81.

Another fixed baffie 94 extends downwardly from the rear housing wall 15 and terminates in the center of the enclosure '!2 below the upturned lip 89 on the end of the baffle 81, forming a lower mouth 95 to which the waste rock is discharged. The air blast passing between the baiiies 8c and El, is sharply deflected by the bame 9 and continues upwardly in the enclosure l2. At the top of the enclosure 12 a suitable fiue 96 is supported on the top wall '!3 for discharging the processed material. A slanted bafile 9'! extends downwardly from the front wall of the housing 1 5 to deflect a blast into the flue 96, and a manually controlled damper 98 may be mounted in the fiue to further control the blast through the apparatus. After passing out through the fiue 99 the asbestos fibers are separated from the air blast by a conventional cyclone separator or other suitable means as are well known in the art.

The separation of the rock particles from the asbestos fibers is quite simple. It will be remembered, that the larger rock particles were defieeted for reprocessing in passing through the throats 46 and 57. The mixture of asbestos and rock particles which is carried by the air blast between the baffles 8t and 8! contains only small rock particles, the degree of fineness being determined by the adjustment of the throats 46 and 51. Moreover, it will be understood that the proportion of the asbestos fibers in the mixture at this stage is relatively high. As can be seen in Fig. 3, the air blast makes substantially a 180 turn after leaving the lower baffle 81. This large angular deflection causes much of the material to impinge on the baflle 94 and tend to fall downwardly through the mouth 95.

The blower pipe 82 is positioned near the mouth and discharges air through a series of perforations 99 spaced along the top and bottom thereof. Air is supplied to the blower pipe 32 from a suitable outside source (not shown), and is regulated by an intake valve 86 as is seen in Fig. 1. The air jetted through the top perforation 33 opposes the tendency of the mixture to fall through the mouth 95. A turbulent condition is created, and the swirling of the material separates the asbestos fibers from the rock particles. The jets of air through the perforations 89 are adjusted by means of the valve 84 to a flow which supports the asbestos fibers, but will not support the more compact rock particles which fall downwardly and are carried out by the waste pipe M3. The lower jets 83 aid in forcing the rock into the pipe 39, and keep the passage is open for continuous flow.

The control of the separation process can now be more fully understood. By adjustment of the valve its and the baiiie control handle 93, the opposed air blasts at the mouth 95 may be proportioned so as to support different diameters and lengths of asbestos fibers without supporting the rock particles. To this end it should be reme .bered that the size of the rock particles in the air blast will be largely determined by the adjustment of the throats it and 5?, while the fiber structure of the asbestos is dependent upon the stratification of the raw ore.

It will be readily appreciated by those skilled in the art that a major advantage of the preferred apparatus lies in the fact that the material is handled in a continuous fiow without the necessity of screening or the use of water as would tend to destroy the separability or length of the asbestos fibers.

While the particular apparatus herein shown and described in detail is fully capable of obtaining the aforementioned objects and advantages, it is to be understood that I do not wish to limit myself to the details of construction or design herein shown, except as defined in the appended claims.

I claim:

1. Apparatus for classifying and separating air-suspended particles comprising: a housing having a lower entrance opening and an upper discharge opening; means defining a plurality of passageways in said housing communicating with said entrance opening to receive a blast of air having different kinds of particles suspended therein, said passageways being formed to deflect said air blast through sharply angled turns in a generally ascending path; means forming a chute opening into the passageway spaced after the first of said angled turns for catching particles displaced from said air blast and returning said particles for recirculation; a chamber in said housing connected to the upper one of said passageways and to said discharge opening; spaced downwardly inclined baffles in said chamber defleeting said air blast into the center thereof, the upper of said baffles being pivotally mounted to adjust the degree of constriction of said air blast, said lower bafiie having an inner upturned end portion; a fixed baffle in said chamber inclined downwardly in opposition to said lower baiiie and having the lower end thereof spaced below said upturned end portion of the latter to define a mouth generally opposed to the direction of iicw of said air blast; and intake pipe means spaced below said mouth and having vertically directed apertures therein to deliver upwardly dir cted air jets.

Apparatus for classifying and separating airsuspended particles comprising: a housing having a lower entrance opening and an upper dis charge opening; means defining a plurality of passageways in said housing communicating with said entrance opening to receive a blast of air having different kinds of particles suspended therein, said. passageways being icrined to defiect said air blast through sharply angled turns in a generally ascending path; means forming a chute opening into the passageway spaced after the first of said angled turns for catching particles displaced from said air blast and returning said particles for recirculation; a chamber in said housing connected to the upper one or" said passageways and. to said discharge opening; downwardly inclined baiiies in said chamber de fleeting said air blast into the center thereof, the upper of said baffles being pivotally mounted to adjust the degree of constriction of said air blast, and said lower baiile having an inner upturned end portion; a fixed battle in said chamber inclined downwardly in opposition to said lower ca-fie and having the lower end thereof spaced below said upturned end portion of the latter to define a mouth generally opposed to the direction or fiow of said air blast; intake pipe means spaced below said mouth and having vertically directed apertures therein to deliver upwardly directed air jets; and means connected to the bottom or" said chamber below said pipe means for catching particles falling t rough said upwardly directed air jets.

3. Apparatus for classifying and separating air suspended particles comprising: a housing having a lower entrance opening and an upper is" charge opening; baffles secured within said housing and defining a plurality of passageways co1nmunicating with said entrance opening to receive a blast of air having difierent kinds of particles suspended therein, said passageways being formed to deflect said air blast through sharply angled turns in a, generally ascending path; gate members cooperatively mounted with said baffles to constrict said air blast in said passageways; means forming a chute opening into the passageway spaced after the first of said angled t irns for catching particles displaced from said air blast and returning said particles for recirculation; a

chamber in said housing connected to the upper 1 one of said passageways and to said discharge opening; spaced downwardly inclined baiiles in said chamber deflecting said air blast into the center thereof, the upper of said baffles being pivotally mounted to adjust the degree of constriction of said air blast, and said lower bafde having an inner upturned end portion; a fixed baiiie in said chamber inclined downwardly in opposition to said lower baffle and having the lower end thereof spaced below said upturned,

end portion of the latter to define a mouth generally opposed to the direction of flow of said air blast; and intake pipe means spaced below said mouth and having vertically directed apertures therein to deliver upwardly directed air jets.

4. Apparatus for classifying and separting airsuspended particles comprising: a housing hav ing a lower entrance opening and an upper discharge opening; baflies secured within said housing and defining a plurality of passageways communicating with said entrance opening to receive a blast of air having different kinds of particles suspended therein, said passageways being formed to deflect said air blast through sharply angled turns in a generally ascending path; gate members cooperatively mounted with said baiiles to constrict said air blast in said passageways; means forming a chute opening into the passageway spaced after the first of said angled turns for catching particles displaced from said air blast and returning said particles for recirculation; a chamber in said housing connected to the upper one of said passageways and to said discharge opening; spaced downwardly inclined baffles in said chamber deflecting said air blast into the center thereof, the upper of said bafflcs being pivotally mounted to adjust the degree of constriction of said air blast, and said lower having an inner upturned end portion; a fixed baiiie in said chamber inclined downwardly in opposition to said lower baflie and having the lower end thereof spaced below said upturned end portion of the latter to define a mouth gen erally opposed to the direction of flow of said air blast; intake pipe means spaced below said mouth and having vertically directed apertures therein to deliver upwardly directed air jets; and means connected to the bottom of said chamber below said pipe means for catching particles fallthrough said upwardly directed air jets.

5. Apparatus for classifying and separating air-suspended particles comprising: a housing having a lower entrance opening and an upper discharge opening; baiiies secured within said housing and defining a plurality of passageways communicating with said entrance opento receive a blast of air having dinerent kinds of particles suspended therein, said passageways being formed to deflect said air blast through sharply angled turns in a generally ascending path; gate members cooperatively mounted with said baiiies to constrict said air blast in said passageways; external operating m ans connected to said gate members to ad-- just the opening therethrough; means forming a chute opening into the passageway spaced after the first of said angled turns for catching particles displaced from said air blast and returning said particles for recirculation; a chamber in said housing connected to the upper one of .said passageways and to said discharge opening; spaced downwardly inclined battles in said chamber deflecting said air blast into the center thereof, the upper of said bafiies being pivot-ally mounted to adjust the degree of constriction of said blast, and said lower bafiie having an inner upturned end portion; external operating connected to said upper bafiie to adjust the degree of constriction of said air blast; a fixed baffle in said chamber inclined downwardly in opposition to said lower baiile and having the lower .end thereof spaced below said upturned end portion of the latter to define a mouth generally opposed to the direction of flow of said air blast; intake pipe means spaced below said mouth and having vertically directed apertures therein to deliver upwardly directed air jets; and means including a hopper and a suc tion discharge pipe connected to the bottom of said chamber below said pipe means for catching particles falling through said upwardly directed air jets.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Number Re. 15,275 21,945 241,513 247,694 247,946 393,411 485,571 1,074,040 1,244,788 1,310,917 1,380,322 1,418,735 1,427,117 1,434,843

Name Date Mettler Jan. 24, 1922 Cox Nov. 2, 1858 Ross May 17, 1881 Schultz Sept. 27, 1881 Pomeroy Oct. 4, 1881 Willis Nov. 27, 1888 Barnard Nov. 1, 1892 Bettington Sept. 23, 1913 Steckle Oct. 30, 1917 McCool July 22, 1919 Lindsay et a1. May 31, 1921 Plaisted June 6, 1922 Moore et a1 Aug. 29, 1922 Raymond Nov. 7, 1922 Number Number Name Date Dolbear Sept. 11, 1928 Mett Dec. 31, 1929 Lykken July 1, 1930 Fischer Nov. 7, 1933 Solomon Jr. June 13, 1939 Rogers Nov. 12, 1940 Zakel Mar. 27, 1951 FOREIGN PATENTS Country Date Switzerland Dec. 16, 1925 Germany Sept. 14, 1931 Austria June 25, 1934 Great Britain Mar. 11, 1935 Germany June 14, 1935 

